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The method of catalytic isotope exchange of tritium gas in solid phase was studied in this paper in order to label high molecular weigth alcohols. The specific activity of the product was 1-10 Ci/mmol and the radiochemical purity more than 98%. The ground glass used as reaction media and Pd/C as catalyst, permitted to obtain a high values of reaction yields and incorporated activity. [ABSTRACT FROM AUTHOR]

The ³H-ATP is a key substance in biotechnological research. This paper proposes a method to obtain ³H-ATP in two steps: --Labelling of AMP with tritium by thermical activation and isotopic exchange methods. --Enzymatic conversion from ³H-AMP to ³H-ATP. The quality parameters of both labelled compounds (specific activity, chemical and radiochemical purity) such as different factors in the labelling process affecting the biological activity of the product, were determined. [ABSTRACT FROM AUTHOR]

Tritium-labeled dipeptide Gly-Leu was administered to noninbred guinea pigs by intracardiac injections, and to Wistar rats--intra-intestinally, through a specially implanted catheter. It was found that after intravenous and intraintestinal administration of isotope-labeled dipeptide the "low-molecular label" was bound by serum proteins. Dissociation of the complexes "low-molecular label"--serum protein in 8 M solution of urea has evidenced a predominantly reversible character of interaction between the low-molecular ligand and protein macromolecule. The results obtained should be taken into consideration during assay of protein absorption from gastro-intestinal tract of laboratory animals.